JP2004040377A - Wireless communication system, and wireless communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To decrease a level variable range that is a requirement of the reception ALC (automatic level control) and the transmission APC (automatic power control) provided in a slave station apparatus in order to compensate attenuation due to rainfall and attenuation due to distance. <P>SOLUTION: The slave station apparatus is configured in a wireless communication system to include: a first fixed attenuator 16 for attenuating a signal received from a master station apparatus depending on a prescribed preset attenuation; a reception power level detection means 18 for detecting the reception power level of the received signal attenuated by the first fixed attenuator 16; a transmission power level control means 20 for controlling the transmission power level of a transmission signal on the basis of the reception power level detected by the reception power level detection means 18; and a second fixed attenuator 21 for attenuating the transmission signal controlled by the transmission power level control means 20 in response to the prescribed attenuation set in interlocking with the first fixed attenuator 16. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a wireless communication system and a wireless communication method capable of performing wireless data communication at substantially the same power level between a master station device and one or more slave station devices. The present invention relates to a power control unit (transmitting APC and receiving ALC) provided in a slave station device for compensating, which can reduce a level variable range.
[0002]
[Prior art]
2. Description of the Related Art In recent years, with the rapid spread of data communication, a demand for a high-speed network has been increasing. However, high-speed lines provided by wire require installation and wiring work for each house, and indoor wiring work is required even when changing the layout of the house. . Therefore, the spread of wireless communication networks that do not require complicated wiring work for each door is desired.
As a system that meets such needs, for example, Japanese Patent Application Laid-Open No. 2000-299848 (Publication 1) discloses a two-way wireless system in which an existing CATV (cable television) network is used and the terminal portion of the network is replaced with wireless. A CATV system has been proposed. This is, for example, a point-to-multipoint (PMP: Point to Point) transmission / reception of data between a master station device (base station) and a plurality of slave station devices (subscriber stations) using microwaves to millimeter waves of 10 GHz or more. Multi Point) is a two-way wireless communication system that can be used for communication services requiring broadband, such as providing video data such as movies on demand, in addition to Internet connection services.
[0003]
FIG. 5 is a schematic configuration diagram of a general PMP two-way wireless communication system.
When data is transmitted from the slave station device 10a to the master station device 10b, in the slave station device 10a, a signal output from the slave station modem 11a is adjusted by the slave station radio 12a to adjust the power level, convert the frequency, and perform signal conversion. Is amplified, a radio signal is transmitted via the slave station antenna 13a. On the other hand, in the master station device 10b, the signal transmitted from the slave station device 10a is taken into the master station radio device 12b via the master station antenna 13b and subjected to amplification, frequency conversion, etc., and then to the master station modem 11b. Is input to
In the PMP two-way wireless communication system, the power level of a signal (uplink signal) reaching the master station device 10b needs to be a power level that can be received by the master station device 10b. That is, the automatic power control (transmission APC) unit included in the slave station wireless device 12a sends the signal to the master station device 10b in accordance with the amount of attenuation of the radio signal between the slave station wireless device 12a and the base station device 10a which changes depending on rainfall, distance, and the like. It is necessary to adjust the transmission power level of the base station device 10b so that the power level of the uplink signal reaching the master station device 10b (hereinafter referred to as master station arrival power level) approaches a predetermined power level.
[0004]
An example of a method of adjusting the transmission power level by the transmission APC section in the slave station device 10a is disclosed in JP-A-6-37681 (Japanese Patent Laid-Open Publication No. 6-37681) or JP-A-2002-16505 (Japanese Patent Publication No. 3505). The station device 10a detects the reception power level of the signal (downlink signal) received from the master station device 10b, and raises (compensates) the transmission power level by an amount corresponding to the decrease in the reception power level due to rainfall or the like. )) Has been proposed.
FIG. 3 shows a schematic configuration of the slave station device 10a2 in the communication system disclosed in the above publications 2 and 3.
As shown in the figure, in the slave station device 10a2, the down signal received from the receiving antenna 13a1 is converted to an intermediate frequency (IF) by the down converter 15 via the low noise amplifier 14. Here, the reception signal level of the downstream signal converted into the intermediate frequency is detected by the output detection device 18 and fed back to the reception ALC 17. Thus, the downstream signal converted into the intermediate frequency is taken into the slave station modem 11a via the diplexer 19 after the power level is kept constant by the reception ALC 17.
On the other hand, the upstream signal output from the slave station modem 11a is taken into the APC 20 via the diplexer 19. Here, the received power level of the downlink signal detected by the output detection device 18 is input to the APC 20.
As a result, the APC 20 can compensate the transmission power level by the change in the reception power level. The upstream signal whose power level is suitably controlled by the transmission APC is converted to a transmission frequency (RF) by the up-converter 22 and further amplified as necessary by the power amplifier 23 before being transmitted from the transmission antenna 13a2. You.
As described above, in the conventionally known slave station device 10a2, since the path of the upstream signal and the path of the downstream signal pass through the same space, the attenuation is assumed to be substantially the same in both, and the reception in the downstream signal is assumed to be the same. By increasing the transmission power level of the uplink signal by an amount corresponding to the attenuation (decrease) of the power level, it is possible to maintain the master station reaching power level at a predetermined power level.
[0005]
[Problems to be solved by the invention]
By the way, a signal in a quasi-millimeter wave band to a millimeter wave band having a frequency of 20 GHz or more, which is generally used in the PMP two-way wireless communication system, is greatly attenuated by the influence of rainfall.
FIG. 4 shows the relationship between the distance between the base station device 10b and the slave station device 10a2 constituting the PMP bidirectional wireless communication system and the reception input level of the reception ALC 17 in the slave station device 10a2. This is an example in which the weather is divided into fine weather (と) and rainfall (▲). However, it was assumed that the output power level of the master station device 10b was 20 dBm, the radio frequency was 26 GHz, and the rainfall was 120 mm / h.
As is clear from the figure, the reception input level of the reception ALC is attenuated according to the distance (26 dB / km in fine weather) and further decreases by 21 dB in rain. As a result, the reception input level in the reception ALC 17 is different between when the weather is at the shortest distance (50 m) where the attenuation is the smallest and when it is rainy when it is at the longest distance (1 km) where the attenuation is the largest. A difference of about 47 dB results.
Therefore, in order to perform suitable compensation (operation) irrespective of the distance from the master station device 10b or the weather condition in the slave station device 10a2 which can be installed under such conditions, the reception ALC 17 must be 47 dB or more. Level variable range. Similarly, for the transmission APC 20 that controls the power level of the uplink signal, in order to realize good linearity (when the reception power level drops by 1 dB, the transmission power level is raised exactly by 1 dB). , 47 dB or more is required.
As described above, in the conventionally-known slave station device 10a2, the reception ALC can be reduced without discriminating the attenuation amount of the reception power level in the downlink signal between attenuation by distance (distance attenuation) and attenuation by rainfall (rainfall attenuation). In addition, due to the configuration for compensating by the transmission APC, the reception ALC 17 and the transmission APC 20 need to function for an attenuation amount equal to or greater than the sum of the distance attenuation and the rain attenuation.
However, it has been difficult in circuit design to secure a large level variable range (47 dB or more in the above example) for the reception ALC 17 and the transmission APC 20.
Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a power control unit (receive ALC and transmit APC) provided in a slave station device for compensating rain attenuation and distance attenuation. An object of the present invention is to provide a wireless communication system and a wireless communication method capable of reducing a required level variable range.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a slave station device which detects a reception power level of a signal received from a master station device, and detects a signal transmitted to the master station device based on the detected reception power level. In a wireless communication system for determining a transmission power level, a slave station device includes: a first fixed attenuator for attenuating a signal received from a master station device according to a predetermined attenuation amount; Reception power level detection means for detecting a reception power level of a reception signal from the master station attenuated by the attenuator, and transmission to the master station apparatus based on the reception power level detected by the reception power level detection means Transmission power level control means for controlling a transmission power level of a signal to be transmitted; and a transmission signal controlled by the transmission power level control means, to the first fixed address. Configured as a wireless communication system characterized by comprising; and a second fixed attenuator for attenuating in accordance with the predetermined attenuation amount set in conjunction with Teneta.
Here, it is desirable that the predetermined amount of attenuation be provided in multiple stages and be appropriately switched according to the distance between the master station device and the slave station device.
Thereby, for example, when the distance between the master station device and the slave station device is long, the attenuation in the fixed attenuator is set to be large, and when the distance is short, the attenuation is set to be small. This makes it possible to narrow the input range of the signal input to the transmission power level control means, thereby reducing the variable range (control range) required for the transmission power level control means, which facilitates design. Performance can be improved.
[0007]
Further, the present invention can be considered as a wireless communication method characterized by the method of determining the transmission power level applied to the wireless communication system according to any one of the first to third aspects. In a wireless communication method for detecting a reception power level of a signal received from a device and determining a transmission power level of a signal to be transmitted to the master station device based on the detected reception power level, a slave station device includes: A first step of attenuating a signal received from the apparatus in accordance with a predetermined attenuation amount, and detecting a reception power level of the reception signal from the master station attenuated in the first step A second step of controlling the transmission power level of a signal to be transmitted to the master station device based on the reception power level detected in the second step; And a fourth step of attenuating the transmission signal whose transmission power level has been controlled by the step according to the predetermined amount of attenuation set in conjunction with the first step. Wireless communication method.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments and examples of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention. The following embodiments and examples are mere examples embodying the present invention, and do not limit the technical scope of the present invention.
Here, FIG. 1 is a schematic configuration diagram of a slave station device 10a1 according to the embodiment of the present invention which configures the wireless communication system A, and FIG. 2 is a diagram illustrating the slave station device in the slave station device 10a1 according to the embodiment of the present invention. FIG. 3 is a diagram showing a relationship between a distance to a master station device and an input signal level, FIG. 3 is a schematic configuration diagram of a conventionally known slave station device 10a2 in the wireless communication system A, and FIG. FIG. 5 is a diagram illustrating a relationship between a distance between the device and a master station device and an input signal level, and FIG. 5 is a diagram illustrating a schematic configuration of a general PMP wireless communication system.
[0009]
First, the overall configuration of the wireless communication system A according to the embodiment of the present invention is the same as the general PMP two-way wireless communication system shown in FIG.
Next, a schematic configuration of the slave station device 10a1 included in the wireless communication system A will be described with reference to FIG.
The slave station device 10a1 includes a slave station modem 11a, a slave station radio 12a, a reception antenna 13a1, and a transmission antenna 13a2. Further, the slave station radio 12a includes a low noise amplifier 14, a down converter 15, a fixed attenuator 16 (corresponding to a first fixed attenuator), a reception ALC 17, an output detection device 18 (corresponding to a reception power level detection means), and a diplexer 19. , A transmission APC 20 (corresponding to transmission power level control means), a fixed attenuator 21 (corresponding to a second fixed attenuator), an up-converter 22, and a power amplifier 23.
That is, a signal (downlink signal) transmitted from a master station device 10b (see FIG. 5) not shown in FIG. 1 is received by the receiving antenna 13a1, and the received signal is given a predetermined gain by the low noise amplifier 14. After that, the frequency is converted to an intermediate frequency (IF) by the down converter 15. The frequency-converted signal is attenuated by a predetermined amount by the fixed attenuator 16, and then the output power is detected by the output detector 18 and fed back to the reception ALC 17. As a result, the frequency-converted signal is taken into the slave station modem 11a via the diplexer 19 after the power level is maintained at a predetermined level.
On the other hand, a signal (up signal) output from the slave station modem 11a is taken into the transmission APC 20 via the diplexer 19. Here, the reception power level detected by the output detection device 18 is input to the transmission APC, and power level control is performed according to the amount of attenuation of the downlink signal. Next, after the signal after the control is attenuated by a predetermined amount by the fixed attenuator 21, the signal is converted into a radio frequency (RF) by the up-converter 22 and further amplified by a predetermined gain by the power amplifier 23. It is transmitted to the master station device 10b via the transmission antenna 13a2.
As described above, the slave station device 10a1 configuring the wireless communication system A according to the embodiment of the present invention assumes that the attenuation in the path of the uplink signal and the path of the downlink signal are substantially the same, The basic operation is the same as that of the conventionally known slave station device 10a2, in which the transmission power level is increased by an amount corresponding to the decrease, thereby maintaining the master station arrival power level at a predetermined power level.
[0010]
The slave station device 10a1 according to the embodiment of the present invention includes: the fixed attenuator 16 for attenuating the reception power level of the reception signal converted into the IF frequency by the down converter 15 by a predetermined attenuation amount; The difference is that the transmission APC 20 includes the fixed attenuator 21 that attenuates the transmission power level of the transmission signal whose power level is controlled by the transmission APC 20 by the predetermined attenuation amount set in conjunction with the fixed attenuator 16. Here, it is assumed that the attenuation of the fixed attenuators 16 and 21 can be changed by operating the DIP switch 23 so that the attenuation can be selected.
Accordingly, the DIP switch is operated in accordance with the distance between the slave station device 10a1 and the master station device 10b, and the amount of attenuation in the fixed attenuators 16 and 21 is appropriately switched, whereby the signal input to the reception ALC 17 is obtained. Can reduce the difference due to the distance between the reception ALCs and the degree of freedom in the design of the reception ALC 17 and the transmission APC 20, thereby contributing to a reduction in production costs.
[0011]
Next, the operation resulting from the addition of the fixed attenuators 16 and 21 will be described with reference to FIG.
Here, FIG. 2 shows a distance (hereinafter abbreviated as a distance between base stations) between the master station device 10b and the slave station device 10a1 constituting the wireless communication system A according to the present embodiment. The relation between the reception input level of the reception ALC 17 in the station device 10a1 and the time when the weather is fine (□, ○, Δ) and when it rains (Δ, ●, ▲) are shown separately. However, the output power level of the master station device 10b was set to 20 dBm, the radio frequency was set to 26 GHz, and the rainfall was torrential rain of 120 mm / h. The attenuation of the fixed attenuators 16 and 21 is provided in three stages of 0 dB (no attenuation), 10 dB and 20 dB, and is switched by the dip switch 23 in accordance with the distance between base stations.
First, consider the case where the distance between base stations is short (50 to 400 m in the present embodiment).
In this case, the attenuation in the fixed attenuators 16 and 21 may be set to a large value (20 dB in the present embodiment). (Corresponds to the area (1) shown in FIG. 2)
As a result, the downlink signal transmitted from the master station device is attenuated by 20 dB by the fixed attenuator 16 before being input to the reception ALC 17, so that the input power level of the reception ALC 17 is reduced by the fixed attenuator 16. 20 dB smaller than the conventional known device.
On the other hand, by adding the attenuator 16, the output power level of the transmitting APC 20 that performs power level control in accordance with the feedback signal of the ALC 17 can be reduced by the amount of attenuation compared to a conventionally known case without the fixed attenuator 16. Just rise. For this reason, in the present embodiment, the fixed attenuator 21 set in conjunction with the fixed attenuator 16 is provided on the transmission side, and the rise is attenuated (canceled), thereby compensating the transmission signal to the master station device 10b. I keep a balance.
Next, consider the case where the distance between base stations is relatively long (450 to 650 m in the present embodiment).
In this case, the attenuation in the fixed attenuators 16 and 21 may be set to an intermediate value (10 dB in the present embodiment). (Corresponding to the area of (2) shown in FIG. 2) As a result, the downlink signal transmitted from the master station apparatus is attenuated by 10 dB by the fixed attenuator 16 before being input to the reception ALC 17, so that The input power level of the reception ALC 17 is 10 dB lower than that of a conventionally known device without the fixed attenuator 16.
As described above, the increase in the output power level of the transmission APC 20 is canceled by the fixed attenuator 21, and the compensation balance for the transmission signal to the master station device 10b is maintained.
Finally, consider the case where the distance between base stations is long (700 m or more in this embodiment). (Corresponding to the area of (3) shown in FIG. 2)
In this case, the attenuation in the fixed attenuators 16 and 21 may be set to a small value (0 dB in the present embodiment).
As a result, the downlink signal transmitted from the master station device is input to the reception ALC 17 without being attenuated by the fixed attenuator 16. Therefore, the output power level of the transmission APC is the same as the power level of the conventional device without the fixed attenuator 16. Of course, since the attenuation by the fixed attenuator 16 is not performed, the output power level of the transmission APC 20 is the same as that of the conventional device without the fixed attenuator 16, and the attenuation by the fixed attenuator 21 is unnecessary.
As is clear from the above description and FIG. 2, according to the slave station device 10a1 constituting the wireless communication system A according to the present embodiment, although the reception input level of the reception ALC 17 is attenuated according to the distance and rainfall, By operating the dip switch 23 according to the distance between the base stations and appropriately changing the amount of attenuation by the fixed attenuators 16 and 21, it is possible to reduce the difference between the reception input levels of the reception ALC 17. For example, in the case of the present embodiment, it is possible to reduce the difference between the reception input levels to 27 dB.
As a result, the degree of freedom in designing the reception ALC 17 and the transmission APC 20 provided in the slave station device 10a1 to compensate for rainfall attenuation and distance attenuation can be improved, which can contribute to a reduction in manufacturing cost.
[0012]
【Example】
In the above embodiment, the mode in which the attenuation of the fixed attenuator is switched in three stages has been described. However, the number of steps may be two or four or more.
For example, if the number of steps is four or more, the level variable range required for the reception ALC 17 and the transmission APC can be further reduced.
In addition, not only the case where the signal is attenuated by the fixed attenuator but also the case where the signal is amplified can be treated in the same manner by considering it as negative attenuation.
[0013]
【The invention's effect】
As described above, according to the present invention, a slave station device detects a reception power level of a signal received from a master station device, and transmits a signal to be transmitted to the master station device based on the detected reception power level. In a wireless communication system for determining a power level, a slave station device attenuates a signal received from a master station device in accordance with a predetermined attenuation amount, and a first fixed attenuator. Receiving power level detecting means for detecting the received power level of the received signal from the master station apparatus attenuated by the above, and transmitting the received signal to the master station apparatus based on the received power level detected by the received power level detecting means. Transmission power level control means for controlling the transmission power level of the signal; and the transmission signal controlled by the transmission power level control means, Configured as a wireless communication system characterized by comprising; and a second fixed attenuator for attenuating in accordance with the predetermined attenuation amount set in conjunction with the over data.
Here, it is desirable that the predetermined amount of attenuation be provided in multiple stages and be appropriately switched according to the distance between the master station device and the slave station device.
Thereby, for example, when the distance between the master station device and the slave station device is long, the attenuation in the fixed attenuator is set to be large, and when the distance is short, the attenuation is set to be small. The input range of the signal input to the transmission power level control means can be narrowed (uniform regardless of the distance), and the variable range (control range) required for the transmission power level control means can be reduced. Is possible, and the ease of design can be improved.
[0014]
Further, the present invention can be applied to a wireless communication method characterized by the method of determining the transmission power level applied to the wireless communication system according to any one of the first to third aspects. In a wireless communication method for detecting a reception power level of a signal received from a device and determining a transmission power level of a signal to be transmitted to the master station device based on the detected reception power level, a slave station device includes: A first step of attenuating a signal received from the apparatus according to a predetermined attenuation amount, and detecting a reception power level of the reception signal from the master station attenuated in the first step A second step of controlling a transmission power level of a signal to be transmitted to the master station device based on the reception power level detected in the second step; And a fourth step of attenuating the transmission signal whose transmission power level has been controlled by the step according to the predetermined amount of attenuation set in conjunction with the first step. Wireless communication method.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a slave station device 10a1 according to an embodiment of the present invention that configures a wireless communication system A.
FIG. 2 is a diagram illustrating a relationship between a distance between a slave station device and a master station device and an input signal level in the slave station device 10a1 according to the embodiment of the present invention.
FIG. 3 is a schematic configuration diagram of a conventionally known slave station device 10a2 in a wireless communication system A.
FIG. 4 is a diagram showing a relationship between a distance between a slave station device and a master station device and an input signal level in a conventionally known slave station device 10a2.
FIG. 5 is a diagram showing a schematic configuration of a general PMP wireless communication system.
[Explanation of symbols]
A: wireless communication system 10a1 slave station device 10a2 slave station device 10b master station device 11a slave station modem 11b master station modem 12a slave station wireless device 12b master station wireless device 13a slave station antenna 13b master Station antenna 13a1 Reception antenna 13a2 Transmission antenna 14 Low noise amplifier 15 Down converter 16 Fixed attenuator 17 Reception ALC
18 output detection device 19 diplexer 20 fixed attenuator 21 transmission APC
22 ... up converter 23 ... power amplifier

Claims (4)

In a wireless communication system, a slave station device detects a reception power level of a signal received from a master station device and determines a transmission power level of a signal to be sent to the master station device based on the detected reception power level.
The slave station device is
A first fixed attenuator for attenuating a signal received from the master station device in accordance with a predetermined attenuation amount set in advance;
Reception power level detection means for detecting a reception power level of a reception signal from the master station device attenuated by the first fixed attenuator;
Transmission power level control means for controlling a transmission power level of a signal to be transmitted to the master station device based on the reception power level detected by the reception power level detection means;
A second fixed attenuator for attenuating the transmission signal controlled by the transmission power level control means according to the predetermined attenuation amount set in conjunction with the first fixed attenuator;
A wireless communication system comprising: 2. The wireless communication system according to claim 1, wherein the predetermined amount of attenuation is provided in multiple stages and can be appropriately switched. The wireless communication system according to claim 2, wherein the predetermined amount of attenuation is switched according to a distance between the master station device and the slave station device. In a wireless communication method, a slave station device detects a reception power level of a signal received from a master station device and determines a transmission power level of a signal to be sent to the master station device based on the detected reception power level.
The slave station device is
A first step of attenuating a signal received from the master station device in accordance with a predetermined attenuation amount set in advance;
A second step of detecting a reception power level of a reception signal from the master station device attenuated in the first step;
A third step of controlling a transmission power level of a signal to be transmitted to the master station device based on the reception power level detected in the second step;
A fourth step of attenuating the transmission signal whose transmission power level has been controlled in the third step in accordance with the predetermined attenuation amount set in conjunction with the first step;
A wireless communication method comprising:

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